Talking about the Motorola MPx220, it seems for Motorola it becomes more than 'just' a Windows Mobile device but a complete solution (as well as the MPx Pocket PC Phone Edition). According to Business Wire, Research in Motion (RIM) and Motorola are working on BlackBerry solutions for the MPx-line:

WResearch In Motion today announced plans to enable BlackBerry connectivity on the Motorola MPx and MPx220 mobile devices. Through RIM's BlackBerry Connect licensing program, the Motorola MPx and MPx220 will be able to connect to BlackBerry services including BlackBerry Enterprise Server and BlackBerry Web Client.

"The MPx and MPx220 are the ultimate email devices for mobile
professionals who want to stay in touch with their business, friends and
family." said Michael Tatelman, Vice-President and General Manager, MOTOPro
Products, Motorola Inc. "Constant access to email is an essential part of
everyday business and private life for busy people and the MOTOPro
Innovation Platform provides the flexibility to deliver world class
connectivity solutions such as RIM's BlackBerry Connect."

"We are pleased
to work with Motorola to provide BlackBerry connectivity support for the
Motorola MPx and MPx220," said Mark Guibert, Vice President, Corporate
Marketing at Research In Motion. "With BlackBerry Connect, Motorola
customers will be able to choose the proven and popular BlackBerry service
and enjoy always-on, push-based access to email on the go."

While I still don't like the BlackBerry device concept (in my opinion a
Pocket PC Phone Edition is the better choice) I like the RIM messaging solution
because it's the best push E-Mail solution you can get today. If RIM features
the MPx-line, it makes it even more attractive for corporate customers.